# stu_info = {"吕红": "数据库", "肖杨": "Python", "丁锦": "英语",
#             "周婷": "线性代数", "李娟": "数据库", "周玲玲": "Java"}
# stu_info["赵红"] = "Java"
# stu_info["周玲玲"] = "Python"
# del stu_info["周婷"]
# for item in stu_info.items():
#   print(item)
# target_value = "Python"
# keys_for_value = [key for key ,value in stu_info.items()
#                   if value == target_value]
# for key in keys_for_value:
#     print(key)

# data = ({"张三": "1234567", "李四": "0987654", "王五": "7654321"})
# locked_users =[]
# a =0
# while True:
#     name = input("请输入用户名：")
#     if name not in data and name not in locked_users:
#         print("用户不存在。")
#         continue
#     elif name in locked_users:
#         print("该用户已被锁定")
#         continue
#     password = input("请输入密码：")
#     if data[name] == password:
#         print("登录成功")
#         break
#     else:
#         a +=1
#         print("密码错误，三次后账户锁定")
#         if a == 3:
#             locked_users.append(name)
#             print("该用户已被锁定")
#             break

str1 =input("输入字符串")
str2 = sorted(set(str1))
print(str2)